In a communication system in which a base station and a mobile terminal wirelessly communicate with each other, a bearer is set from the mobile terminal to a node of a core network via the base station. When the mobile terminal performs handover from a source base station to a target base station, the number of bearers and the quality for each bearer are maintained.
There is known a communication system that transmits a channel capacity assigned until now between the source base station and the mobile terminal, to the target base station of the handover when the handover is performed (e.g. International Publication Pamphlet No. WO99/31823). There is known a communication system that readjusts the capacity of the bearers when the handover is performed (e.g. Japanese National Publication of International Patent Application No. 2003-524335).